Method of assembling lead-in conductors for vacuum tubes



Jan. 4, 1944. LQHMANN 2,338,381

METHOD OF ASSEMBLING LEAD-IN CONDUCTORS FOR VACUUM TUBES Filed March 1, 1941 ,iinverdor:

Femvz lax/MAM Patented Jan. 4, 1944 METHOD OF ASSEMBLING LEAD-IN CON- DUCTORS F OR VACUUM TUBES Franz Lohmann, Hamburg, Germany; vested in the Alien Property Custodian Application March 1, 1941, Serial'No. 381,303 In Germany February 8, 1940 2 Claims.

This invention relates to the manufacture of discs or cups made of pressed glass and carrying electric conductors in order to serve as the bottom of electron tubes, these conductors being the inleads thereof.

The invention aims to obviate certain disadvantages of the prior methods of manufacturing these structures, as will be understood from the following description and the accompanying drawing, in which Fig. 1 is a sectional view showing a structure of this kind, Fig. 2 is a partially sectioned view of a device according to the present invention used in the manufacture of such structures.

As shown in Fig. 1 by way of example, the structure or article to be manufactured consists of a disc A, made of pressed glass, and conductors 2 sealed into this disc. The disc A may be cup-shaped.

According to the invention the dies l, 5 are both arranged to revolve on a horizontal axis, as will be seen in Fig. 2, and the vitreous material for making the disc A is in the shape of a ring 6 supported by conductors 2 and midway between the dies. The vitreous material is thus easier to heat and the gas Jet 4 hence may be less intense than in the case of former devices in which the glass mass is supported in contact with the surface of a metal die. The gas jet 4 is adjusted so that the dies shall not be unduly heated. By the dies revolving about an axis common to them the softening glass is prevented from dripping. The glass also does not contact with the dies until the pressing operation takes place. Consequently, the loss of heat of the glass is less than in the case of prior devices where the glass is heated while in contact with the surface of a die. Furthermore, the expenditure in heat being less than in the case of such prior devices, the conductors 2 are less liable to oxidize and thereby to deteriorate the glass from which the disc A is to be made. Moreover, as the conductors 2 are located at their ends in the dies I, I they are cooled by the dies, which thus in their turn aim to prevent the conductors from oxidizing.

In using the pressing dies l, 5 shown in Fig. 2 the conductors 2 are mounted in the recesses B of die I and the glass ring 6 is inserted over these conductors, whereupon the die 5, having bores C for receiving the conductors 2, is likewise inserted over them. The structure I, 2, 6, 5 is then set rotating while at the same time the ring 8 is softened by the gas jet 4. When the ring is sumciently soft, die 5 is advanced toward die I so that ring 6 is compressed and thus converted into the disc A into which at the same time the conductors 2 are sealed.

What is claimed is:

1. The method of manufacturing an'assembly of a plurality of lead in conductors for vacuum tubes which comprises, securing said conductors in a support in predetermined spaced relationship to each other so that they may be rotated about a common horizontal axis, then placing a ring of glass about said conductors so said ring is held thereby in spaced relationship to said support, then rotating said support and said conductors about a horizontal axis while said ring is subjected to a softening heat while turning therewith, and thereafterwhen said ring has been sufficiently softened, pressing said ring around the respective conductors by means of said support and a cooperating die member.

2. The method of manufacturing an assembly of a plurality of lead in conductors for vacuum tubes which comprises securing said conductors near one end thereof in a die member in predetermined spaced relation to each other, positioning a ring shaped mass of glass on said conductors so said mass is supported by said conductors in spaced relationship with said die member, heating said mass over a flame while turning said die member about a horizontal axis until said mass becomes soft enough for pressing and there-= after pressing said mass into the desired shape between said die member and a second die member which cooperates therewith. 

